Threat Description

Uedasan

Details

Summary

XM/Uedasan is a macro virus that infects Microsoft Excel 95 workbooks. It contains
a destructive payload.

Removal

Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Technical Details

Variant:Uedasan.A

XM/Uedasan.A activates when a sheet is deactivated in an infected document. At this
point it creates a new workbook, infects it and saves it to Excel's startup directory
with a name "TDK-MAC.XLS". Then it removes the following menu items: "View/Toolbars...",
"Tools/Macro...", "Window/Unhide", "Tools/Protection" and "Format/Sheet/Unhide".

When this is done, the virus infects every workbook when a sheet is activated. It
adds a hidden sheet to a workbook which will contain the virus code module. This sheet
is protected with a password "uedasan". It also removes the title, subject, author,
keywords and comments from the summary information of the active workbook.

After the active workbook has been infected, the virus will activate its payload from
August to the end of year.

In August, it attempts to delete everything from the root of "C:" directory; and from
September to December if the time is less than 6:00am, it attempts to delete everything
from the current directory.

Variant:Uedasan.B

This variant works in a similar fashion like the XM/Uedasan.A.

When it infects Excel, the file created to the startup directory is named "#1SLIDER.XLA"
and during infection this virus will check for several specially named modules as
well. For example, if it founds a sheet named "pldt" it shows a message box with the
following text:

WARNING : VIRUS DETECTED! NAME : 'MERALCO'

The payload is the same as the XM/Uedasan.A.

Variant:Uedasan.D

XM/Uedasan.D is functionally identical with XM/Uedasan.B.

Description Details: Analysis: Sami Rautiainen, F-Secure

SUBMIT A SAMPLE

Suspect a file or URL was wrongly detected? Submit a sample to our Labs for analysis